Abstract : Intensity and frequency of clear air turbulence increases as an acceleration variable of the rawinsonde observation, defined as 'adjusted acceleration', increases. Adjusted acceleration represents the magnitude of the rawinsonde acceleration without respect to sign which has been adjusted, by regression techniques, for a small dependence upon the average rate of ascent for that observation. This acceleration variable is used to describe large scale variations in rawinsonde ascensional rates. Pilot reports of clear air turbulence were supplied the Weather Bureau by the Federal Aviation Administration. Equations for estimated turbulence probabilities as a function of adjusted acceleration were obtained for three ten-day collection periods. (Author)